Nowadays the portable apparatus market such as a mobile phone is increasing and a design of the apparatus as well as advanced functions or capabilities is becoming more important for the market. Furthermore, a curved surface of a casing is becoming popular for the purpose of better handling or looks. However, current electronic components mounted on a board in a mobile phone are usually arranged on a planar wiring board and therefore, it is difficult to arrange the components with efficiency in the casing formed by the curved surface. In addition, because the freely-designed shape may cause problems such as an increasing of a bulk of the apparatus, the apparatus often has to compromise its design. As a result, a commercialization of a wiring board having a curved surface corresponding to the outer curved surface of an apparatus, in which electronic components can be efficiently arranged, is strongly desired.
By the way, packaging boards (e.g. semiconductor devices), in which electronic components such as semiconductor packages or semiconductor chips are mounted on wiring boards, are packaged in the portable apparatus whose size is required to be reduced. At a bottom of the packaging board, pads (ball bump 124, connecting terminal) called BGA (Ball Grid Array) as described in Patent Document 1, CSP (Chip Size Package) or WL-CSP (Wafer Level Chip Size Package), for example, are arranged in a grid pattern (see FIG. 12). This type of packaging board is used popularly because more terminals can be implemented in a narrow area.
A method to print a cream solder on a pad of a wiring board using a metal mask, mount an electronic component on the wiring board and fuse the solder by a reflow process is used for connecting the electronic component on the wiring board mechanically and electrically.
[Patent Document 1] JP-3395164B (FIG. 1)
[Patent Document 2] JP Patent Kokai Publication No. JP-P2004-266074A (FIG. 1)
[Patent Document 3] JP Patent Kokai Publication No. JP-P2002-151853A (FIG. 7)
[Patent Document 4] JP Patent Kokai Publication No. JP-P2005-303172A (FIG. 5)